As part of the deal, though, IBM wanted Microsoft to provide a version of BASIC, a programming language for beginners, along with a few simple games to show it off. What it came up with was "DONKEY.BAS," a silly game about a car that has to avoid donkeys in the road.

"Actually, it was myself and Neil Konzen at four in the morning with this prototype IBM PC sitting in this small room. IBM insisted that we had to have a lock on the door, and we only had this closet that had a lock on it, so we had to do all our development in there, and it was always over 100 degrees, but we wrote late at night a little application to show what the BASIC built into the IBM PC could do. And so that was DONKEY.BAS. It was, at the time, very thrilling."

"We were surprised to see that the comments at the top of the game proudly proclaimed the authors: Bill Gates and Neil Konzen. Neil was a bright teenage hacker who I knew from his work on the Apple II (who would later become Microsoft's technical lead on the Mac project) but we were amazed that such a thoroughly bad game could be coauthored by Microsoft's cofounder, and that he would actually want to take credit for it in the comments."

In 2001, to show off how far the company had come, Microsoft built a 3D version of "DONKEY.BAS," called "DONKEY.NET," where the aim is to hit donkeys with a car. You can download a version of it, but it's difficult to get running on modern systems.

Gates became a massive fan of another classic Microsoft game: He was such a fan of Minesweeper that he had to delete it from his computer to stay productive — still, he would end up sneaking into his executives' offices to play it.